/*
  UDPSendReceive.pde:
  This sketch receives UDP message strings, prints them to the serial port
  and sends an "acknowledge" string back to the sender

  A Processing sketch is included at the end of file that can be used to send
  and received messages for testing with a computer.

  created 21 Aug 2010
  by Michael Margolis

  This code is in the public domain.

  adapted from Ethernet library examples
*/


#include <ESP8266WiFi.h>
#include <WiFiUdp.h>


#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library.
// On an arduino UNO:       A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO:   2(SDA),  3(SCL), 
//On an arduino esp8266:   D2(SDA),  D1(SCL), 
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


#ifndef STASSID
#define STASSID "Xiaomi_2G_free" //无线名称
#define STAPSK  "" //无线密码
#endif

unsigned int localPort = 8888;      // local port to listen on

// buffers for receiving and sending data
char packetBuffer[UDP_TX_PACKET_MAX_SIZE + 1]; //buffer to hold incoming packet,


WiFiUDP Udp;


void showtext(String text) {
  display.clearDisplay();
  display.setTextSize(2);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0, 0);            // Start at top-left corner
  display.println(F("Recv:"));
  display.setTextSize(2);
  display.println(text);
  display.display();

}

void setup() {
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); // Don't proceed, loop forever
  }

  // Show initial display buffer contents on the screen --
  // the library initializes this with an Adafruit splash screen.
  display.display();

  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin(STASSID, STAPSK);

  
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print('.');
    delay(500);
  }
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());
  Serial.printf("UDP server on port %d\n", localPort);
  Udp.begin(localPort);

   display.clearDisplay();
  display.setTextSize(2);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0, 0);            // Start at top-left corner
  display.println(F("IP:"));
  display.println(WiFi.localIP());
  display.setTextSize(2);
  display.print(F("PORT:"));
  display.println(localPort);
  display.display();
}

void loop() {
  // if there's data available, read a packet
  int packetSize = Udp.parsePacket();
  if (packetSize) {
    Serial.printf("Received packet of size %d from %s:%d\n    (to %s:%d, free heap = %d B)\n",
                  packetSize,
                  Udp.remoteIP().toString().c_str(), Udp.remotePort(),
                  Udp.destinationIP().toString().c_str(), Udp.localPort(),
                  ESP.getFreeHeap());

    // read the packet into packetBufffer
    int n = Udp.read(packetBuffer, UDP_TX_PACKET_MAX_SIZE);
    packetBuffer[n] = 0;
    Serial.println("Contents:");
    Serial.println(packetBuffer);
    showtext(String (packetBuffer));


  }

}

/*
  test (shell/netcat):
  --------------------
	  nc -u 192.168.esp.address 8888
*/